Tubular Steel Fabrication: Rotary Draw Bending

So you need some tubes bent. You need them bent tightly, precisely, and efficiently. You need rotary draw bending.

Rotary draw bending is the most common type of bending in tubular steel fabrication, and it’s the only type of bending that allows for extremely tight, accurate bends.

What Makes Rotary Draw Bending Awesome?

Rotary draw bending is the only type of bending process that can use mandrels – solid metal tools inserted in the tube to help it retain its shape during the bending process. The mandrel reduces tooling marks and allows a thin-walled tube to keep its shape. This means thin-walled pieces can only be produced through rotary draw (unless you like warped tubing).

Rotary draw uses die sets to control the process. This means parts are consistent and accurate when they come off the bender. Everything is automated and the use of tooling allows for consistently higher quality production.

Constantly improving CNC technology allows for complex part manufacturing. Like the use of tooling, entirely electric machinery saves time, improves efficiency, and cuts down on manual labor costs. It also allows for incredibly complex bends that were physically impossible with hydraulic machinery.

The most notable benefit of rotary draw bending is its excellence in tight radius bends. Rotary draw is the only type of bending that allows for extremely tight, accurate bends.


The amount of tooling in rotary draw bending is both a blessing and a curse. The machine requires setup of a bend die, clamp die, pressure die, and other components. If you need to purchase dies, it makes later design changes and simple projects more trouble than they’re worth.

Rotary draw benders also have issues creating continuous bends. The clamp die requires a straight section of tubing to latch onto.

Finally, large radius bend dies can be difficult or impossible to produce. If your product requires a large bend radius, rotary draw bending is not the process for you.

Other Types of Bending

Aside from rotary draw, there are three other standard types of bending: compression bending, roll bending, and freeform bending. All three of these methods are more friendly for large radius bends and projects that don’t require a large amount of tooling.

However, if you need precise, tight, high-quality bends, rotary draw bending is the right method for you.